Exclude category

by

To exclude a category, you need to know its ID. You can then exclude it like this (please not the minus before the ID):

$args = array( 'posts_per_page' => 4, 'cat' => -the_category_id_to_put_in);

The WP Query class reference has more information if you need it: http://codex.wordpress.org/Class_Reference/WP_Query#Category_Parameters